In a design of an integrated circuit, various cells having predetermined functions are used. Pre-designed layouts of standard cells or memory cells are stored in cell libraries. During the integrated circuit design process, the pre-designed layouts of the standard cells are retrieved from the cell libraries and placed at selected locations in an integrated circuit layout. Routing is then performed to connect components of the standard cells with each other using interconnect lines. Next, an optical proximity correction (OPC) is performed and a set of masks are generated to manufacture the integrated circuit using semiconductor manufacturing processes.
Because of the complexity of various designs, an electronic design automation (EDA) tool is used to simulate and verify the integrated circuits at various levels of abstraction under the direction of a designer, in some instances. From design to mask fabrication, the EDA tool performs various tasks, such as design rule checking, layout versus schematic checking, layout parasitic extraction and resistance-capacitance (RC) extraction.